The world's largest aircraft - part plane, part airship and part helicopter - has been unveiled in the UK in all its 300ft (91m) long glory.

Known as the HAV304, the giant aircraft has been displayed at Cardington in Bedfordshire in the only hangar big enough to accommodate the 113ft (34m) wide and 85ft (26m) high monster.

Created by Hybrid Air Vehicles Ltd and first flown in the USA, the ultra-green HAV304 project has just received a £2.5 million grant from the UK Government.

Due to fly in the UK later this year, the HAV304 is designed to stay airborne for up to three weeks and can be used for a variety of functions including surveillance, communications and delivering aid.

The plan is that the HAV304 will eventually lead to the development of the Airlander 50, which would be able to transport 50 tonnes of freight.

The huge aircraft effectively combines the best of aeroplane, airship and helicopter design. HAV reckons there could be a world market for between 600 and 1,000 of these aircraft.

For the time being, the company plans to produce around 10 a year for the next four or five years. This is expected to lead to the creation of 1,800 jobs in the Bedfordshire area.

Business Secretary Vince Cable said today : "The growing aerospace sector has the potential to generate thousands of new jobs and billions of pounds to the UK economy in contracts.

"That is why so much effort is being put in by government and industry to ensure we stay ahead of the competition and build on our strong position as second in the world for aerospace."

He went on: "As part our long-term industrial strategy we are jointly funding £2 billion of research and development into the next generation of quieter, more energy-efficient and environmentally-friendly planes.

"That includes backing projects like HAV's innovative low-carbon aircraft which can keep us at the cutting edge of new technology. Here is a British company that has the potential to lead the world in its field."

HAV chief executive Stephen McGlennan said: "This Government support shows that HAV has a credible way of solving one of the aerospace industry's key challenges - creating a viable low-carbon aircraft which can travel for days and for thousands of miles without refuelling, landing without the need for airports. It is a great story of a British company leading the world."

The HAV304 was first developed for the US government as a long-endurance surveillance aircraft but it fell foul of defence cutbacks.

Getting the aircraft to the UK late last year involved the use of 15 gigantic containers, with four days needed to unload the equipment using a 50-tonne crane and a 100-tonne one.

The dimensions of the aircraft relate to it in its fully-inflated state, with the hull being filled with safe, inert helium.

The hangar at Cardington is 812ft (248m) long, 157ft (48m) high and 180ft (55m) wide.